WO1989012451A1

WO1989012451A1 - Improved flowable insecticidal delivery compositions and methods for controlling insect populations in an aquatic environment

Info

Publication number: WO1989012451A1
Application number: PCT/US1989/002703
Authority: WO
Inventors: Richard Levy
Original assignee: Lee County Mosquito Control District
Priority date: 1988-06-24
Filing date: 1989-06-21
Publication date: 1989-12-28
Also published as: US4985251A; JP2788522B2; AU630102B2; JPH03505459A; EP0423189A4; EP0423189A1; AU3851589A

Abstract

Superabsorbent solid organic polymers which absorb over 100 times their weight in water are used in flowable aquatic environment insect population control compositions of varying viscosities. Methods for using the superabsorbent polymer insecticidal delivery agents for the control of aquatic environment insect populations, including mosquito population control methods, in an area needing aquatic environment insect population control treatment or in a dry area that is exposed to need aquatic environment insect population control, are described.

Description

IMPROVED FLOWABLE INSECTICIDAL DELIVERY

COMPOSITIONS AND METHODS FOR CONTROLLING INSECT

POPULATIONS IN AN AQUATIC ENVIRONMENT

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation-in-part of my application entitled "Improved Insecticidal Compositions and Methods for Controlling a Population of Insects in an Aquatic Environment," Serial No. 032,532, filed April 1, 1987.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a variable-viscosity, insecticidal delivery formulation composed of a liquid carrier, e.g., water or oil, and one or more solid superabsorbent polymers with one or more liquid or solid insecticidal or noninsecticidal film-forming or surface-active agents, ovicides, larvicides, pupicides, insecticides, biological control agents, pathogens, parasites, microbial control agents, insect growth regulators, conventional toxicants, pesticides, or chemosterilants, with or without herbicides or attractants, repellents, phermones, alcohols, diluents, or other additives. The present invention also relates to a method of applying the insecticidal delivery composition with one or more active insecticidal ingredients, with or without one or more herbicides or other additives, as variable-viscosity sprays or sols to an aquatic environment having a natural population of aquatic environment insects, for the purpose of controlling that population of insects. The present invention also relates to the use of the insecticidal delivery composition for a pretreatment application to an aquatic insect dry habitat in order to control that population of aquatic insects that will breed when the insect habitat becomes flooded by rain or tides. This invention further relates to a facile method of combining two or more active insecticidal ingredients in a liquid carrier, e.g., water or oil, with one or more film-forming agents, and one or more superabsorbent polymers, with or without one or more herbicides or other additives, to formulate variable-viscosity insecticidal delivery compositions that are flowable (i.e., sprayable, pumpable, or injectable) for ground or aerial application. The application of superabsorbent polymers makes possible the mixing of active insecticidal and herbicidal ingredients that would otherwise be difficult or substantially impossible to mix homogeneously in. a liquid carrier, e.g., water or oil, as joint- or multiple-action formulations for spray application. Furthermore, this invention relates to the use of one or more superabsorbent polymers in the formulation of a variety of sprayable/flowable insecticide compositions to synergize, enhance, activate, carry, disperse, release, stabilize, bind, couple- encapsulate, agglomerate, regulate, thicken, suspend, preserve, protect, etc., one or more of the active and/or inactive formulation components in the flowable formulation and/or in the target aquatic, semi-aquatic, or pretreatment environment (s) in which the formulation is applied, in a manner that will provide improved flowable formulations, more efficient formulating (mixing) procedures, more efficient application, and/or generally improve the insecticidal efficacy (performance) of the resultant formulation against the targent organism(s). General Background

In particular, the present invention is directed against mosquitoes that breed in permanent or semipermanent, natural or artificial, aquatic habitats. Mosquitoes of major importance to be controlled by the present invention are species of the genera of Aedes, Anopheles, Cules, Culiseta, Coquillettidia, Deinocerites, Mansonia, Orthopodomyia, Psorophora, Uranotaenia, and Wyeomyia. It is the main objective of this invention to direct the use of the flowable insecticidal delivery of composition(s) for the control of the immature aquatic states of various species of mosquitoes before they become biting adults capable of being a nuisance and/or transmitting a disease. This technique is costeffective and reduces the environmental and health hazards that can result when insecticides are extensively broadcast over large areas for the control of the adult stages. In addition to mosquitoes, other species of aquatic environment insects such as biting and nonbiting midges, black flies, moth flies, crane flies, horse flies, deer flies, hover or flower flies can constitute a nuisance and often a health threat to humans and livestock. Thus, their growth as a population, if unchecked, can be detrimental. The medical and veterinary importance of various species of mosquitoes and other important aquatic environment insects are discussed in detail by Robert F. Harwood and Maurice T. James in, Entomology in Human and Animal Health, Seventh Edition, 1979, MacMillan Publishing Co., Inc., New York, N.Y., which is incorporated herein by reference. Therefore, the scope of the present invention also relates to the use of the flowable insecticidal delivery composition with one or more active insecticidal ingredients, with or without one or more herbicides or other additives, for controlling various species of aquatic environment insects other than mosquitoes.

Various compositions and methods for controlling and killing insects are well known. A number of patents discuss the use of pesticides or insecticides. U.S. Patent No. 3,535,423 discloses a wettable powder pesticide concentrate that may be dispersed in water. This is described as allowing the otherwise insuluble pesticide to become soluble in water. U.S. Patent No. 4,267,280 discloses controlled release pesticides and their preparation. These pesticides are described as polymers with a macro-molecular backbone and pendant groups having pesticidal groups chemically linked thereto and prepared by reacting a pesticide having a replaceable hydrogen with a multifunctional isocyanate to form an adduct which is then reacted with a polyol polymer substrate. U.S. Patents Nos. 4,400,391 and 4,401,456 disclose the use of alginate gel beads to encapsulate bioactive materials to provide for their controlled release. The patents describe beads being made to either float or sink and they may contain insecticides. These beads are also described as acting as carriers to place this bioactive material near the tarσer species, for example, a floating bead containing a herbicide releasing the herbicide in close proximity to floating aquatic weeds or the beads falling through foliage to release a herbicide into the soil. U.S. Patent No. 4,344,857 contains a disclosure that is similar to those immediately above; however it involves encapsulation by xanthate derivatives and does not disclose the ability to be used in conjunction with an aqueous environment.

A number of patents describe the use of substances other than pesticides to control the growth of insects. U.S. Patent No. 4,053,627 discloses a controlled release system for juvenile hormones in aqueous environments. This is described as being accomplished with alginate gel discs comprising alginate, a solubilizing agent, and a salt which yields cations, and containing the juvenile hormone. U.S. Patent No. 4,160,033 discloses a method for the control of mosquitoes by the use of film-forming materials. The method is disclosed as involving the use of a film of organic material which reduces the surface tension of the body of water, and subsequently causes the mosquito larvae and pupae to drown.

At the present time, ground and aerial application of non-petroleum film-forming agents such as Arosurf® MSF for Mosquito control is performed mainly of spraying the technical liquid or vigorously agitated suspensions of the filmforming agent and water. However, technical film-forming agent(s) such as Arosurf® MSF applied as conventional liquid sprays are usually adversely effected by wind drift and cannot penetrate dense vegetation at the low recommended application rates. Therefore, most of the costly insecticidal film-forming agent impinges on the vegetation and does not reach the water where the mosquitoes are breeding and/or is translocated by the wind to areas not intended for application. In addition, the use of water as a diluent for application of large volumes for easier vegetative penetration without overdosing requires frequent high-speed/high-shear agitation or the use of high-pressure/high-shear, waterinjection systems to adequately suspend the film-forming agent in the water for accurate application rates. Mosquitocidal film-forming agents such as Arosurf® MSF are virtually insoluble in water, and therefore require continuous or frequently repeated high-shear agitation to effectively suspend or resuspend the Arosurf® MSF in the water carrier.

The aqueous absorbency mechanism of acrylic-based superabsorbent polymers has been described by the Chemdal Corporation (Arlington Heights, Illinois 60004) in their Technical Data Sheets on Aridall® Superabsorbent Polymers. The absorbency of acrylic-based superabsorbent polymers is due to carboxylic groups located on the backbone of the superabsorbent polymer. When water contacts the superabsorbent polymer, these groups solvate rapidly and develop mutually repulsive negative charges. This causes the superabsorbent polymer to uncoil and absorb many times its weight in water. Crosslinking prevents solution of the superabsorbent polymer. The aqueous medium rapidly becomes oriented on the surface of the sueprabsorbent polymer by virtue of hydrogen bonding. The resulting gel has remarkable ability to hold the aqueous medium even under pressure. Superabsorbent polymers hold fluids by a physiochemical mechanism.

None of the prior art methods or compositions for controlling insect populations are without disadvantages. One major problem associated with many of the aforementioned compositions and methods of the prior art is their inability to sulultaneously apply immiscible, or otherwise incompatible substances to the area to be treated. it has been found that while film-forming materials, when combined with water and ovicides, larvicides, pupicides, insecticides, pesticides, conventional toxicants, biological control agents, microbial control agents, pathogens, parasites, chemosterilants, or insect growth regulators, with or without herbicides or diluents such as attractants, repellents, peromones, alcohols, etc., may produce improved insect controlling efficacy over single active component formulations, problems with mixing the ingredients homogeneously often result. For

' example, blends of Arosurf® MSF (a film-forming agent) and water or technical and/or water-base blends or Arosurf® MSF and various formulations of Bacillus thuringiensis var. israelenses (B.t.i.), or Bacillus sphaericus or Abate® 4-E do not form homogeneous and stable suspensions when casually mixed, and therefore require frequent and vigorous agitation. When allowed to stand, the components would separate into distinct layers because of the differences in their respective specific gravities, and/or the presence of incompatible active and/or inert formulation ingredients, and therefore these joint- or multiple-action formulations would require continuous agitation and/or reagitation to effectively remix the components just prior to their application. (See Levy et al. 1984, Moscruito News 4:537-543; Levy et al. 1986. Journal of the American Mosquito Control Association 2:233-236.) These mixing and remixing requirements make it very difficult to apply these liquid (aqueous) formulations by conventional means.

While it may be possible to incorporate some known insecticidal components, singly, jointly, or multiply as aqueous or oil-base sprays, these formulations cannot regulate (retard) the release rate of active insecticidal components, and lack the ability to control both mosquito larvae and pupae simultaneously while effectively and spontaneously spreading the active ingredients over the target aquatic habitat.

Since other flowable insecticidal compositions do not have rapid self-spreading characteristics, they require even applications to assure that effective control of the target aquatic insects that may be widely dispersed in the aquaatic habitat. In addition, the other flowable insecticidal components usually affect only one immature developmental stage. However, the use of insecticidal delivery compositions made with one or more superabsorbent polymers of the present invention with, for example, a pupicidal filmforming agent (e.g., Arosurf® MSF,), a larvicidal agent such as B.t.i. or Bacillus sphaericus, and water, have self-spreading potential and can kill mosquito larvae, pupae, or emerging adults rapidly in areas far removed from the initial points of application, significantly better than either of the active formulation components. These formulations can also kill floating eggs and egg rafts of certain species of mosquitoes and also entrap and drown females that oviposit on the surface of the water. Although Arosurf® MSF can kill mosquito larvae and pupae, its impact on larval populations is usually very slow and requires higher application rates than for pupal control.

No single-, joint-, or multiple-action flowable, water-compatible formulations are available that claim rapid larvicidal and pupicidal action with some degree of ovicidal and adulticidal action, self-spreading characteristics, and field persistence. For example, commercial mosquitocidal preparations of Bacillus thuringiensis var israelensis formulated for water-base spray applications (e.g., Vectobac® -AS, Vectobac®-12AS; Teknar®, Teknar® HP-D, Teknar® WDC; Bactimos® Wettable Powder; Skeetal®F), Bacillus sphaericus (BSP-1), Abate® 4-E, Dursban®, Baytex® 4 and Baytex® LC, Furadan®, Baygon® 70% wettable powder, Dimilin® wettable powder, Altosid® Liquid Larvicide are available that have slow or quick immature stage kill potential; however, these do not have rapid multi-developmental stage control potential, do not have self-spreading characteristics, are typically composed of only one active insecticidal ingredient that cannot be simply and rapidly detected or monitored under field conditions by insecticide applicators, and are not formulated with superabsorbent polymers.

Attempts have been made to incorporate film-forming agents such as those described in U.S. Patent No. 4,160,033 with a variety of conventional insecticides in water (See Levy et al. 1984, Mosquito News: 44 pp. 537-543, pp. 592-595; Levy et al. 1986. Journal American Mosquito Control Association 2:233-236). However, these attempts have been unsuccessful because the film-forming agent (i.e., Arosurf® MSF) would readily separate into layers even after vigorous agitation due to incompatibilities of the film-forming agent with water or other insecticides and/or inert ingredients in the formulation. Therefore, the resultant formulations could not be homogeneously mixed to assure that accurate application rates of the active components would be applied in the field against the target aquatic pest. Specific Objects

It is therefore an object of the present invention to provide flowable, aqueous- or oil-base superabsorbent polymer compositions and methods for the pretreated dry habitat control and aquatic control of a population of aquatic environment insects, particularly mosquitoes, which overcome the problems and deficiencies of the prior art.

It is also an object of the present invention to provide flowable aqueous- or oil-base superabsorbent polymer compositions and methods which are easy to prepare (formulate) and use (apply), and which are erodible (biodegradable) and safe to the environment, but which is effective for use in controlling one, but preferably more than one immature stage of a natural population of aquatic environment insects, particularly mosquitoes.

It is further an object of the present invention to provide superabsorbent polymer compositions and methods which can incorporate a wide variety of ingredients into a single flowable, aqueous- or oil base insecticidal delivery information to control a broad spectrum of aquatic environment insect populations, particularly mosquitoes, and to provide for the variable time release of those ingredients.

These and other objects are accomplished by the compositions and methods of the present invention. Specific Aspects

In accordance with one aspect of the present invention, there is provided flowable, aqueous- or oil- base insecticidal delivery compositions for controlling a population of aquatic environment insects, the flowable delivery compositions being applied as a pretreatment before the target habitat is flooded or as a direct treatment to the dquatic habitat. The composition includes at least one superabsorbent polymer, and at lease one insecticidal agent, alone or in combination with a diluent or surface active agent, the superabsorbent polymer and insecticidal agent being present in total amount effective to control the population of aquatic environment insects. The superabsorbent polymer(s) being present at a concentration adapted to allow satisfactory mixing of the formulation components and release modification of the insecticidal agent(s) from the flowable formulation.

In accordance with another aspect of the present invention, there is provided flowable, aqueous- or oil-base insecticidal delivery compositions for controlling a population of aquatic environment insects which includes at least one superabsorbent polymer, and at least one different insecticidal agent which is a film-forming agent, the superabsorbent polymer and agent being present in a total amount effective to control the population of aquatic environment insects, the delivery compositions being applied as a variable-viscosity pretreatment application before the target habitat is flooded or as a direct treatment to the aquatic habitat.

In accordance with yet another aspect of the present invention, there is provided flowable aqueous- or oilbase insecticidal delivery compositions for controlling a population of aquatic environment insects which includes at least one superabsorbent polymer, at least one different insecticidal agent which is a film-forming agent, and at least one additional compound. The additional compound is selected from larvicides; pupidides; ovicides; insecticides; toxicants; pesticides; biological control agents; microbial control agents, pathogens, parasites; insect growth regulators; chemosterilants; and mixtures thereof, with or without herbicides; attractants; phermones; repellents; diluents; alcohols; surface-active agents; etc. The superabsorbent polymer, agent and additional compound are present in a total amount effective to control the population of aquatic environment insects, the flowable, variable-viscosity aqueous- or oil-base delivery compositions being applied as a pretreatment before the target habitat is flooded or as a direct treatment to the aquatic habitat.

In accordance with another aspect of the present invention, there is provided a method for controlling a population of aquatic environment insects which includes the steps of: preparing flowable, variable-viscosity aqueous- or oil-base insecticidal delivery compositions which includes at least one superabsorbent polymer and at least one insecticidal agent which includes a film-forming agent, by a series of variable time/speed blending, and/or salt/electrolyte conditioning treatments; applying said flowable, aqueous- or oil-base insecticidal delivery compositions in an amount effective to control the population of aquatic environment insects, to an aquatic area needing aquatic insect control treatment, the flowable aqueous- or oil-base delivery compositions being applied as a pretreatment before the target habitat is flooded or as a direct treatment to the aquatic habitat.

In accordance with still another aspect of the present invention, there is provided a method for controlling a population of aquatic insects. The method includes the steps of: preparing flowable, variable-viscosity aqueous- or oil-base insecticidal delivery compositions which includes at least one superabsorbent polymer and a least one insecticidal agent which includes a film-forming agent at least one additional compound. The additional compound is selcted from ovicides; larvicides; pupicides; insecticides; conventional toxicants; pesticides; biological control agents; microbial control agents; pathogens; parasites; insect growth regulators; chemosterilants; and mixtures thereof, with or without herbicides; attractants; repellents; pheromones; diluents; alcohols; surface-active agents; etc.; and applying said flowable, aqueous- or oil-base insecticidal delivery compositions in an amount effective to control the population of aquatic environment insects, to an aquatic environment needing aquatic insect control treatment before the target habitat is flooded or as a direct treatment to the aquatic habitat.

The superabsorbent polymers of the present invention are synthetic organic polymers which are solid and hydrophilic absorbing over 100 times their weight in water. Generally, these superabsorbent polymers are chosen from acrylamide and acrylate polymers, co-polymers and terpolymers. These polymers can be suitably crosslinked and/or modified. These superabsorbent polymers are typically in a power, flake, or granular form, adapted to optimize the compatibility and/or release rates of insecticidal components in water or oil and, thereby, enhance the activity of flowable insecticidal formulations against the target aquatic insect.

The acrylamide and acrylate superabsorbent polymers may be, for example, acrylamide alkali metal or alkali metal/aluminum acrylate co-polymers; propenenitrile homopolymers, hydroloyzed, alkali metal or alkali metal/aluminum salts; polymers or propenamide and propenoic acid, alkali metal salts; hydrolyzed acrylonitrile copolymers, and starch graft co-polymers and ter-polymers thereof. All of these are designed to be hydrophilic, absorbing over 100 times their weight in water.

The present invention has been found to be particularly effective in controlling natural populations of mosquito species such as Aedes taeniorhynchus, Aedes sollicitans, Anopheles atropos, and Culex niqripalpus that can breed in brackish/salt water habitats. The use of the invention to control species of fresh or polluted water mosquitoes such as Aedes aegypti, Aedes albopictus, Aedes triseriatus, Anopheles quadrimaculatus, Anopheles crucians, Culex quinquefasciatus, Psorophora columbiae, Psorophora ciliata, Wyomyia mitchelli, Wyeomia vanduzeei, etc., in semipermanent or permanent aquatic envirment areas needing mosquito control treatment is also proposed. Specific Advantages

The present invention provides numerous advantages over prior compositions and methods to control the population of aquatic environment insects such as mosquitoes. For example, the flowable aqueous- or oil-base superabsorbent polymer formulations of the present invention may be composed of one or more of a wide choice of either nontoxic or toxic biological or microbial control agents, pathogens, parasites, insect growth regulators, monomolecular surface films, larvicides, ovicides, pupicides, insecticides; chemosterilants; pesticides, and/or toxicants, with or without herbicides or attractants, repellents, pheromones, diluents, alcohols, etc., depending or the type or nature of the habitat to be controlled, the environmental impact, and/or the type of aquatic developmental stage or insect species to be controlled. The superabsorbent polymer formulations of the present invention are flowable (i.e., sprayable, pumpable orinjectable and are mainly based on water; however, these formulations can also be based on oil. The flowable aqueous- or oil-base superabsorbent polymer formulations of the present invention are biodegradable. They are also storage stable, basically as stable as the individual components; however, increased stability may occur from necapsulation of the active components within the aqueous- or oil-base formulation. Aqueous- or oil-base formulations of the present invention can be of varying viscosities which may be required for a particular application. The flowable formulations of the present invention can have some variable time release, either quick, or gradual, depending on the concentration and types of superabsorbent polymers, in the aqueous- or oil-base formulation. The present invention provides a suspending/compatibility agent to assure homogeneous delivery of joint- or multiple-active, aqueous- or oil-base formulations of otherwise incompatible soluble or insoluble liquid or powdered insectricidal and/or non-insecticidal agents without the necessity of continuous or repetitive high-speed/highshear agitation for effective spray application of the active components. Flowable, variable-viscosity aqueous- or oilbase formulations of the present invention can be used as a pretreatment application to areas that are dry but are known to breed when flooded, thereby assuring that the first broods will be controlled. Also, encapsulation of the active insecticidal agents within the variable viscosity flowable superabsorbent polymer formulation can protect the active components from degradation or decomposition from ultraviolet radiation, microbial action, temperature effects, runoff, etc., when the formulation is applied as a pretreatment application. The present invention is also not restricted to applications to any one type of aquatic environment.

Other objects, aspects and advantages of the present invention will be apparent to one of ordinary skill in the art from the following:

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Surprisingly it has been found that certain superabsorbent polymers constitute a novel class of chemicals useful in flowable aqueous- or oil-base insecticidal delivery compositions for controlling the population of insects in an aquatic environment area needing aquatic environment insect control treatment.

A flowable insecticidal delivery composition is any composition which can carry, or be adapted to carry, insecticidal agent(s), biologically active or biologically inactive agent(s), etc., to the target habitat, natural or artificial, aquatic or dry. In a preferred embodiment, the flowable insecticidal delivery agent is a mixture of one or more superabsorbent polymers and water or oil. Superabsorbent polymers, including starch graft co-polymers, are well known in the art. See, for example, those described in United States Patents Nos. 4,375,535 and 4,497,930 (incorporated herein by reference) which have had uses as adhesives, flocculants, sizes, water-retaining materials for agriculture and water-absorbing materials for sanitary materials. However, the advantages attendant the use of superabsorbent polymers in a flowable aqueous- or oil-base insecticidal delivery composition and more specifically for mosquito control in an aquatic environment, have gone completely unrecognized.

The superabsorbent polymers of the present invention are synthetic organic polymers which are solid and hydrophilic, absorbing over 100 times their weight in water. These superabsorbent polymers are substantially waterinsoluble, and are typically in a powder, flake, or granular form, adapted to optimize the compatibility or release rates of insecticidal components in water and thereby, enhance the activity or efficacy of the aqueous- or oil-base insecticidal formulations against the target aquatic insect.

Generally, these superabsorbent polymers are chosen from acrylamide and acrylate polymers, co-polymers and terpolymers, which may optionally be modified by cross-linking or grafting with, e.g., starch.

The acrylamide and acrylate superabsorbent polymers may be, for example, acrylamide alkali metal or alkali metal/aluminum acrylate co-polymers; propenenitrile homopolymers, hydrolyzed, alkali metal or alkali metal/aluminum salts; hydrolyzed acrylonitrile co-polymers, and starch graft co-polymers and ter-polymers thereof. All of these are designed to be hydrophilic, absorbing over 100 times their weight in water. The resulting hydrophilic polymers can absorb from over one hundred to greater than about 5,000, more typically around 500 to about 1,000, times their own weight in water (measured using distilled water, pH 7.5, 25°C, 760 mm Hg., absorption within about 30 seconds). However, the water absorption or swelling capacity and rates typically vary with each specific superabsorbent polymer.

One class of superabsorbent polymers include combinations of a starch and organic monomers, oligomers, polymers, co-polymers, or ter-polymers. They may be manufactured in a variety of ways, for example, the methods described in United States Patents Nos. 4,375,535 and 4,497,930, and can be, for example, the product of grafting corn starch (amylopectin) with acrylonitrile (an acrylic monomer or oligomer). The superabsorbent polymers can also be acrylics, propenoic or carylonitrile/acrylamide-base polymers or copolymers or ter-polymers that also show superabsorbency properties such as cross-linked or cross-linked modified polymers.

It has also been observed that superasborbent polymers alone, or mixed in water with one or more insecticidal agent(s), have the ability to further swell in water, thereby altering the rates of release of the substance(s) in the formulation. Superabsorbent polymers also have the ability under certain conditions to reform on contract to a crystal or congealed-like consistency similar to their original form when evaporation has caused the water to be removed from the sol or gel-like formulation and then swell or re-gel when additional water is added. This ability to be functional after repetitive periods of wetting and drying is advantageous for pretreatment applications, applications to habitats that experience rapid flooding and drying cycles, and/or for prolonging the release of active components. In addition, insecticides encapsulated in the variable-viscosity sol, gellike, or crystal or congealed-like formulations can be protected from climatological and biological degradation in pretreatment and/or in semipermanent habitats; thereby prolonging their field activity. Storage or shelf life may also be prolonged in several of these formulations.

Non-limiting specific examples of superabsorbent polymers with differential swelling properties, and which are particularly useful as insecticidal delivery agents include:

1) a co-polymer of acrylamide sodium acrylate (Terra-Sorb GB);

2) hydrolyzed starch-polyacrylonitrile (TerraSorb);

3) 2-propenitrile, homo-polymer, hydrolyzed, sodium salt or poly (acrylamide-co-sodium acrylate) or poly (2-propenamide-co-2-propanoic acid, sodium salt), (Water Lock® Superabsorbent Polymer G-100); 4) starch-g-poly (2-propenamide-co-2-propanoic acid, sodium salt), (Water Lock® Superabsorbent polymer A-100);

5) starch-g-poly (2-propenamide-co-2-propanoic acid), (Water Lock® Superabsorbent polymer A-200);

6) starch-g-poly (2-propenamide-co-2-propanoic acid, potassium salt), (Water Lock® Superabsorbent Polymer A-204);

7) starch-g-poly (2-propenamide-co-2-propanoic acid, mixed sodium and aluminum salt), (Water Lock® Superabsorbent Polymer A-222);

8) poly (2-propenamide-co-2-propanoic acid, sodium salt), (Water Lock® Superabsorbent Polymer G-400);

9) poly-2-propanoic acid, sodium salt, (Water Lock® Superabsorbent Polymer J-500 or Aqua Keep® J-500);

10) sodium polyacrylate superabsorbent polymers {Aqua Keep® J-400 and J-550);

11) starch-g-poly (acrylonitrile) or poly (2-propenamide-co-sodium acrylate, (General Mills SP 5025);

12) starch acrylonitrile co-polymer (Super Sorb/AG Sαrbent);

13) cross-linked modified polyacrylamides (Aquastore® and Aquastore®F);

14) cross-linked acrylics (Aridall® 1078, 1080, 1091, 1092, or 1098); and

15) cellulosic laminates of poly-2-propenoic acid, sodium salt (Water Lock® Superabsorbent Laminates L-413, L-415, L-425, L-435, or L-513).

Superabsorbent polymers are generally nontoxic, biodegradable, and relatively inexpensive to buy or produce. See, for example, U.S. Patents 3,661,815 and 4,159,260, which are incorporated herein by reference.

An insecticidal agent of the present invention is a compound which is effective in an aqueous or oil base superabsorbent polymer formulation in controlling a population of aquatic environment insects in an aquatic area needing aquatic insect control treatment. In a preferred embodiment, insecticidal agents include film-forming agents, ovicides, larvicides, pupicides, pesticides, insecticides, toxicants, chemosterilants, biological control agents, pathogens, parasites, microbial control agents, and insect growth regulators. These insecticidal agents can be used alone or in combination; however, in a more preferred embodiment, the insecticidal agent contains at least one filmforming agent. Insecticidal agents can also be formulated with herbicides, attractants, repellents, pheromones, or other diluents that enhance the action of the formulations but show insufficient insecticidal activity.

Electrolytes/salts interfere somewhat with the hydrogen bonding. Crosslinked acrylic-baseed superabsorbent polymers always absorb less aqueous medium when electrolytes/salts are present. Normally, the addition of water or water-based insecticidal formulations to various concentrations of superabsorbent polymers, or vica versa, can form sols or gels of various consistencies (viscosities) or stiffnesses that may or may not be flowable. However, highshear mixing or the addition of various salts/ electrolytes can break or interfere with the gel structure or the hydrogen bonding, thereby producing flowable (sprayable) superabsorbent polymer/insecticide aqueous formulations that have the desired viscosity. Viscosity modification will mainly be a function of the active and/or inactive formulation components, the water absorption characteristics or the superabsorbent polymer (i.e., the type and amount of superabsorbent polymers), shear time and strength used to mix the formulation and/or the concentration and type of salts/electrolytes used to modify the sol or gel consistency of the formulation. Therefore, the viscosity of the aqueous formulation containing one or more superabsorbent polymers can be altered to achieve optimum flowability, droplet size and quantity, and thereby improve the general ground or aerial application characteristics of the formulation for maximum control of the target aquatic insect. Furthermore, active insecticidal ingredients encapsulated in the viscous/semi-viscous but flowable aqueous (or oil base) superabsorbent polymer formulation can be protected from degradation from the effects of ultra violet radiation, volatilization, temperature, microbial activity, evaporation, run-off, etc., particularly when used in pretreatment habitats. Furthermore, evaporation of water from the flowable, aqueous superabsorbent/pesticide formulation can result in a solid congealed-like encapsulated matrix (as described in U.S. Patent Application No. 032,532, the substance of which is incorporated herein by reference) thereby protecting the active components for prolonged periods until release of the insecticidal ingredient is triggered when the preaquatic (pretreatment) habitat is flooded with water.

Film-forming agents that are mosquitocidal are generally water-immiscible organic chemicals which form a monomolecular or duplex films on water. The chemicals are generally nonionic, nonvolatile and water immiscible liquids. They may have a low freezing point, a boiling point above the maximum air temperature of the environment into which they are placed, and are capable of rapid and spontaneous spreading with high respreading potentials.

Examples of liquid, semisolid, or solid filmforming or surface-active agents useful in conjunction with the present invention for insecticidal and/or noninsecticidal purposes are: the organic chemicals described in U.S. Patent No. 4,160,033, which is herein incorporated by reference; and organic chemicals that reduce the water surface tension to greater than 31 dynes/cm and/or have an HLB No. greater than 10. Film-forming agents such as 1-propanol, tridecyl alcohol, 2-ethyl butanol, 2-ethyl hexanol, 1-hexanol, acetone, xylene, decyl alcohol, polyoxyethylene (20) sorbitan trioleate, polyoxyethylene alkyl aryl ether, polyoxyethylene (5) sorbitan monoleate, isostearyl alcohol containing 20 oxyethylene groups, sorbitan monoleate, isostearyl alcohol containing 10 oxyethylene groups, Morwet® surfactants, cetyl alcohol, stearyl alcohol, etc. HLB stands for "Hydrophile-Lipophile Balance," as defined in THE ATLAS HLB SYSTEM, Atlas Chemical Industries, Inc. (4th printing), 1963. The HLB number is an indication of the percentage of the hydrophilic portion of the nonionic emulsifier molecule, as defined on pages 3 and 18 of this reference.

A pupicide is any material that can kill that specific developmental stage of certain aquatic insects called a pupa. Pupicides are usually chemicals that kill pupae directly by forming petroleum or nonpetroleum films on the surface of water that cause the pupae to drown. This stage is nonfeeding and directly precedes the adult stage. Examples of pupicides useful in accordance with the present invention are Arosurf® MSF or other film-forming agents described in U.S. Patent No. 4,160,033. Biological/microbial pupae control agents such as bacteria, fungi, protozoa, viruses, rickettsiae and nematodes may also be used.

Formulations of at least one film-forming agent such as Arosurf® MSF with superabsorbent polymer(s) and water of the present invention into a variable-viscosity flowable formulation allows a significantly more homogeneous and stable (persistent) suspension of Arosurf® MSF and water to form after an initial high shear mixing, as well as larger droplets of the aqueous formulation to penetrate through the vegetative canopy for release of the active film-forming agent into the target aquatic habitat with significantly less wind drift-related problems. In this manner, the need for repeated high-shear mixing/remixing is virtually eliminated. Also, premixed formulations of superabsorbent polymer(s), Arosurf® MSF, and water can be stored as aqueous formulations for direct use for ground or aerial application with little or no additional mixing. In addition, flowable variableviscosity formulations of superabsorbent polymer(s), a filmforming agent (s) such as Arosurf® MSF and water of the present invention can effect a mechanism for slowing down the rate of release of active ingredients, thereby extending the field life or persistence of the mosquito-controlling surface film for a greater period of time than would be expected with conventional technical or agitated non-superabsorbent polymer aqueous formulations of Arosurf® MSF.

The rate of release and/or re-release of the mosquitocidal film-forming agent from the variable-viscosity, flowable superabsorbent polymer formulation will be mainly dependent on the viscosity of the formulation, that is, the ratio of superabsorbent polymer to water (or oil), the water absorbing (swelling) characteristics of the superabsorbent polymer(s), the water quality of the natural or artificial habitat and/or formulation diluent, and on the climatological moisture/water conditions to which the formulation is exposed. High-shear mixing/agitation techniques, the addition of various concentrations of salts/electrolytes (e.g., NaCl, KCl, etc.) to the superabsorbent polymer/pesticide mixture, and/or the use of invert oil techniques are proposed for regulating the viscosity of the flowable superabsorbent polymer formulations.

The proposed variable-viscosity, film-forming agent/superabsorbent polymer(s), flowable, aqueous formulations will resist wind drift (i.e., have greater drift retardant characteristics than simple aqueous spray formulations having no superabsorbent polymer(s)), and initially show a differential ability to float and/or sink depending on the specific gravity of the superabsorbent polymer(s). The addition of various concentration of one or more superabsorbent polymer(s) can also enhance the mixing capability and stability (i.e., reduce or eliminate product(s) separation or stratification) of one or more active and/or inactive formulation components (e.g., formulations of Arosurf® MSF and Bacillus thuringiensis var. israelensis (B.t.i.) or Bacillus sphaericus (B. sphaericus) in a water base; see Levy et al. 1984, Mosquito News, Vol. 4, pp. 537-543 and Levy et al. 1986, Journal of the American Mosquito Control Association, Vol. 2, pp. 233-236) in water by acting as a compatibility or suspending agent. A larvicide is any material that can kill that specific developmental stage of certain aquatic insects called a larva. Larvicides can kill larvae after ingestion of a toxic material, kill on or after contact with the integument, or kill by physical (nontoxic) and/or toxic means by causing the larvae to drown. The larval stage is a feeding stage that usually has several molting or growth phases called instars. For example, in mosquitoes there are four larval instars. The larval stage directly precedes the pupal stage. Examples of larvicides useful in accordance with the present invention include biological control agents or microbial control agents such as Bacillus thuringiensis var israelensis (e.g., Vectobac®, Bactimos®, Teknar®, Skeetal®, Mosquito Attack®,) or Bacillus sphaericus (e.g., BSP-1); conventional toxicants such as Abate^®, Baytex^®, Dursban®, Prentox®, Pyrenone®, resmethrin, malathion, phyrethrins, allethrin, Baygon®, Furadan®, methoxychlor, etc.; and nonpetroleum film forming oils such as Arosurf® MSF. Fungi (such as Lagenidium gigantenum, mycelia and oospores), protozoa, viruses, rickettsiae and nematodes may also be used.

Insect growth regulators (IGRs) are chemicals such as juvenile hormone or anti-juvenile hormone analogues that kill the target aquatic environment insect in one or more immature stages by adversely affecting the molting or developmental cycle. IGRs are not considered to be direct larvicides or pupicides. For the most part, larvae that are exposed to the chemical continue to develop normally until they reach the pupal stage where they die. Examples of IGRs are Altosid®, Dimilin®, and fenoxycarb (Pictyl®).

Insecticides (i.e., pupicides, larvicides, insect growth regulators, pathogens, etc., useful in the present invention are discussed in W.T. Thomas, 1985, Agricultrual Chemicals, Book 1 Insecticides, 1985-86 Revision, The αas Publications, Fresno, California, pp. 1-255, and in George 0. Poinar, Jr. and Gerald M. Thomas, 1978, Diagnostic Manual for the Identification of Insect Pathogens, Plenum Press, New York, pp. 1-218. The use of one or more herbicidal ingredients in the flowable superabsorbent polymer insecticidal compositions is proposed for selected ground or aerial applications, it has been shown that certain aquatic weeds (plants) can provide excellent breeding grounds for disease carrying mosquitoes, and programs aimed at the control of algae and submersed, floating, or emergent plants and/or marginal aquatic plants have been shown to reduce the incidence of various mosquito-transmitted diseases (Dr. Edward 0. Gangstad, 1986, Freshwater Vegetation Management, Thomas Publications, Fresno, California, 377 pp.). For example, aquatic weeds such as coontail, widgeon, grass, waterweed, pondweed, stonewort, bladderwort and filamentous green algae (particularly Spirogyra) have been shown to enhance the development of several species of Anopheles mosquitoes that can be vectors of malaria in the United States and overseas. In addition, Culex tarsalis, a vector of St. Louis and Western encephalitis in the midwestern and western United States, breed in aquatic plant (weed)-choaked irrigation and drainage ditches, seeps, and roadside impoundments. Also, larvae and pupae of mosquitoes of the genera Mansonia and Coquillettidia (potential vectors of Eastern encephalitis) derive their oxygen by puncture from air trapped in hollow aquatic plant stems. In addition, Aedes aegypti, a vector of dengue and yellow fever can breed inside certain water plants. Therefore, the use of herbicides to complement the insecticidal action of the superabsorbent polymers formulations of the present invention is proposed to enhance general mosquito control operations in areas containing significant densities of aquatic plants.

Herbicidal materials proposed for use in the present invention can include one or more materials from the groups, phenoxy compounds; benzoic, acetic acids and phthalic compound; dinitro anilines, nitrites, amides, acetamides and anilides; carbamates; heterocyclic nitrogen derivatives; urea compounds; metal organics and inorganics; petroleum derivatives; phosphates; carbothiolates; cyclic compounds; halogenated hydrocarbons; dinitros; aliphatic acids; and others. Various herbicidal formulations in these groups are discussed in detail in W.T. Thomson, 1986, Agricultural Chemicals, Book II, Herbicides, 1986-87 Revision, Thomson Publications, Fresno, California, 301 pp. and in Dr. Edward O. Gangstad, 1986, Freshwater Vegetation Management, Thomas Publications, Fresno, California, 377 pp. Herbicides and mixtures thereof of specific interest in these groups used for controlling floating weeds, immersed broadleaf weeds, submersed weeds, algae, irrigation and drainage ditch bank weeds, and irrigation and drainage canal weeds, include Acrolein® ammonium sulfamate, Aquazine®, Banvel®, Casoron®, copper, copper sulfate, Cutrine®, Dalapon®, Dichlone®, Diquat®, Endothal®, Fenac®, Karmex®, Monuron®, petroleum solvents, Rodeo®, Roundup®, Simazine®, Sonar, Spike®, 2,4-D, Velpar®, and xylene.

Insect population is used here to refer to one or more group(s) or species of aquatic environment insects that breed in any type of aquatic environment or habitat requiring control treatment. The population as used herein denotes a natural or artificial breeding area and the like or the aquatic insects, pupae, larvae and eggs contained within any geographical area needing aquatic environment insect control treatment. For example, a field, yard, pasture, pot hole, salt marsh, ditch, tire, woods, lake, stream, river, bay, pond, etc., may be treated. Of course, the area needing aquatic environment insect control treatment can be any size and the present invention is only limited by the amount of time, equipment, and material available.

One or more superabsorbent polymers can be used to form flowable, variable-viscosity single-, joint- or multipurpose aqueous- or oil-base formulations composed of one or more insecticides, etc., with or without herbicides or other diluents, solvents, surfactants, attractants, etc., for spray applications by conventional ground or aerial techniques, to control a variety of aquatic insects in a variety of aquatic or preaquatic (pretreatment) habitats. The superabsorbent polymers are used in a variety of flowable aqueous- or oilbase insecticide formulations to synergize, enhance, activate, carry, release, stabilize, bind, agglomerate, regulate, thicken, suspend, neutralize, preserve, etc., one or more of the active and/or inactive formulation components in the flowable formulation and/or in the target aquatic environment(s) in which the formulation is applied, in a manner that will provide improved formulations, and more efficient formulation application.

Variable-viscosity, aqueous- or oil base formulations are flowable and have the ability to release one or more active agents when applied to aquatic environments. The rate of release is dependent on the concentration of formulation components (e.g., superabsorbent polymers, water or oil), the swelling characteristics of the superabsorbent polymer(s), and on the habitat of climatological condition to which the formulation is exposed or released (e.g., dry or wet, pretreatment or aquatic).

Variable-viscosity superabsorbent polymer-based formulations can be formulated by admixing an active agent with one or more superabsorbent polymer(s) and water or oil in any suitable order and them treating said formulation with vigorous or high-shear mixing and/or electrolytes/salts. The ratio of superabsorbent polymer(s) to water or oil depends on the desired viscosity, the nature of the superabsorbent polymer(s) and the method used to render it flowable. The ratio of superabsorbent polymer (s) to water is suitably 0.001:100 to 1.1. The amount of active agent in the flowable formulation is generally 0.00001 to 50 weight percent, preferably 0.0001 to 25 weight percent.

One technique used to render a viscous/semi-viscous aqueous superabsorbent polymer composition flowable is suitably vigorous or high-shear mixing/agitation. Any suitable equipment or technique used to incorporate insecticides into an aqueous emulsion can be suitably used to render a non-flowable superabsorbent-base formulation flowable. Invert oil techniques are also appropriate for mixing and dispensing a highly viscous aqueous superabsorbent polymer formula-ion composed of an insecticide and surface active agent, with or without herbicides or other additives.

Normally, unmixed formulations of superabsorbent polymers and water have a tendency to form gels of such a high viscosity that they are not flowable. An additional technique used to render a viscous superabsorbent polymer composition of the present invention flowable, is the additional of varying concentrations of one or more salt(s)/electrolyte(s) such as sodium chloride. However any suitable salt/electrolyte such as potassium chloride, magnesium chloride, calcium chloride, sodium sulfite, etc., can be employed. These salts/electrolytes have a tendency to interfere with the hydrogen bonding or reduce the hydrophilic bonding of the water to the gel. Also, superabsorbent polymers (e.g., crosslinked acrylics) absorb less water when electolytes are present. This technique can be used by itself or in conjunction with vigorous or high-shear mixing to produce a flowable (i.e., srayable, pumpable or injectable) aqueous superabsorbent polymer formulation having an active ingredient such as insecticide, pesticide or other suitable agents. The technique and degree of viscosity variation are dependent upon the active and inactive ingredients in the superabsorbent polymer formulation. Relevant factors in the degree of viscosity of the formulations are the water swelling characteristics of the superabsorbent polymer (i.e., the type and amount of polymer), water concentration and quality used in the formulation, the shear time and strength used to mix or agitate the formulation and/or the type and concentration of salts/electrolytes used to modify the gel consistency. Using a suitable combination of viscosity varying techniques, the aqueous formulation can be altered to obtain optimum characteristics such as flowability (sprayability), encapsulation of active ingredients, droplet size variations, substrate adherence, slower release rates of active components, and wind drift retardation. It is contemplated that aqueous insecticidal delivery formulations made flowable by vigorous or high shear-agitation and/or the addition of salts/electrolytes can be used to control immature stages of mosquitoes. The superabsorbent polymer (s) used in the flowable aqueous formulation effectively suspends or assists in the mixing of the various active and inactive ingredients, regardless of their compatibility with each other and/or the aqueous medium, to form a homogeneous formulation. Form example, Super Sorb, Arosurf® MSF and Water, or Super Sorb, Arosurf® MSF, water and B.t.i. or B . sphaericus, can be effectively blended together to form a flowable composition with sufficient highshear agitation and/or salt/electrolyte addition such that the ingredients will not separate or partition for an extended period of time. In contrast, under normal circumstances such ingredients would rapidly separate requiring repetitive high shear agitation to render the composition suitably homogeneous for application purposes. As such, large quantities of the formulation can be prepared sufficiently ahead of time and suitably stored until needed, when they can then be applied by conventional spray techniques, without the cumbersome need for repetitive vigorous or highshear reagitiation.

The flowable aqueous compositions also are advantageous when used in aerial applications in their ability to resist wind drift. By altering viscosity significantly, droplet density, size, shape and surface characteristics can be altered to significantly affect the droplet wind resistance, flow, and deposition characteristics when applied with an aerial delivery system. Additionally, aquatic buoyancy characteristics can be suitably altereed in the flowable formulation such as by varying the type and concentration of superabsorbent polymers having different specific gravities, incorporating micro bubbles in the shearing technique, or using high molecular weight additives for the sinking formulations. The variable-viscosity composition also can be suitably modified to effect its surface characteristics with oils, wetting agents, surface-active agents, and the like. Varying concentrations of superabsorbent polymers replaced surface active agents can be incorporated such as to effect the adhesiveness of the water-base spray formulation causing it to cling or adhere to desired strata or plants when delivered to the target pretreatment environment. Other formulation additives can include the above surfactants as well as suitable polymeric agents such as plasticizers, watersoluble polymers, film-forming polymers, etc.

The concentration of superabsorbent polymer(s) in the aqueous or oil base formulations of the present invention has been shown to effect the release rates of the active insecticidal ingredients. In addition, varying the ratio of different types of these superabsorbent polymers of the present invention that have differential water uptake characteristics (e.g., Water Lock® and Aridall® products) in a single formulation may effect a mechanism to further enhance slowrelease characteristics of certain active insecticidal ingredients. In addition, the varying specific gravities (i.e., less than or greater than one) of the superabsorbent polymers and active insecticidal ingredients of the present invention can be used to develop flowable formulations that initially float and/or sink for use in a variety of habitats to optimize the kill of a variety of aquatic insect species.

It should be noted that certain electrolytes/salts (e.g., alkali metal halides such as NaCl) have been shown to interfere with hydrogen bonding of the superabsorbent polymers in an aqueous medium. Also, crosslinked acrylic superabsorbent polymers have been shown to absorb less water when electrolytes are present. This can have an impact on the swelling and population control ability of the flowable insecticidal delivery composition (e.g., the release rate of certain insecticidal agents that are formulated there within). Therefore, it is possible to utilize certain electrolytes/salts in superabsorbent polymer-based formulations as another mechanism to alter (enhance in this case) or adjust the release rate of various active ingredients incorporated in these formulations. The salt/electrolyte content of the aquatic habitat may also have an effect on kill of the target species such as mosquitoes by affecting the superabsorbent polymer swelling, breakdown/decomposition of viscous formulations, and/or release or active insecticidal ingredients encapsulated within the flowable aqueous superabsorbent polymer formulations.

The following are examples of comparative bioassays that demonstrate effective control of larvae, pupae, and/or emerging adults of a variety of mosquito species with single and joint action flowable aqueous formulations of a superabsorbent polymer and one or more insect control agents. Examples demonstrating formulation viscosity modification with high mixing and/or electrolyte/salt conditioning and slow release are also presented. All parts, percentages and ratios are by weight unless otherwise noted.

EXAMPLES I - VII

Data was collected from the use of aqueous insecticidal delivery formulations composed of Super Sorb, Water Lock®, Aqua Keep®, and/or Aridall® superabsorbent polymers and film-forming agent isostearyl alcohol containing two oxyethylene groups (Arosurf® MSF); and a superabsorbent polymer, Arosurf® MSF and B.t.i, or B. Sphaericus; with or without high-shear and salt/electrolyte conditioning. Arosurf® MSF is the only film-forming agent (so-called monomolecular surface film) that is presently registered by the Environmental Protection Agency (E.P.A.) for use as a mosquito larvicide an pupicide and licensed under U.S. Patent No. 4,160,033. B.t.i. products have E.P.A. registration while B. sphaericus (BSP-1) has an E.P.A. experimental use permit pending E.P.A. registration.

Mixing compatibility/viscosity modification evaluations were conducted with high-shear mixing or salt/electrolyte conditioning with formulations of Water Lock®, Aqua Keep®, Super Sorb, Aridall®, and/or Aquastore® F. Superabsorbent polymers, Arosurf® MSF, and water; and a superabsorbent polymer, Arosurf® MSF, B.t.i or B . sphaericus, and water or oil; or a superabsorbent polymer, Arosurf® MSF, 2,4-D, and water; as well as with 50/50 superabsorbent polymer blends. Although similar mixing compatibilities were obtained, the results indicated that salt/electrolyte type and the concentration, and the shear time/strength would vary depending on the superabsorbency of the polymer (s) and the type of insecticide and/or herbicide in the aqueous formulation. Mosquito bioassays indicated that the larvicidal and pupicidal efficacy were generally equivalent.

Film-forming agents such as sorbitan monooleate, oleyl alchol, 75% sorbitan monooleate and 25% 2-ethyl butanol or 2-propanol, oleyl alchohol containing 1 oxyethylene groups, and lauryl ether containing 4 oxyethylene groups were also evaluated as substitutes for Arosurf® MSF. These materials were formulated in water with Super Sorb or Water Lock® G-100 to determine mixing compatibility and viscosity modification only. Although these materials were not evaluated against larvae and pupae, mixing studies indicated that homogeneous formulations were obtained, thereby suggesting that comparable mosquito-controlling efficacy would result. In addition, the insect growth regulators Altosid® Liquid Larvicide and fenoxycarb were also formulated with water, Arosurf® MSF and Super Sorb or Water Lock® G-100, to determine formulation compatibilities. Results indicate that joint-action formulations of these materials can also be utilized.

Various concentrations of salts/electrolytes such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride, or sodium sulfite were used in combination with mild mixing (not high-speed/high-shear) to determine the optimum conditions for viscosity modification and component compatibility of aqueous formulations of Arosurf® MSF, a Super Sorb, Water Lock®, Aqua Keep®, or Aridall® superabsorbent polymer, with or without B.t.i. or B. spaercicus. Results indicated that several types of variable-viscosity superabsorbent polymer compositions of one or more insecticides and water were homogeneous, stable, and flowable could be formulated by varying the electrolyte (s)/salt(s) concentration and type.

In general, the data indicates that liquid filmforming or surface-active agents can be initially mixed with a superabsorbent polymer, alone, or in combination with water or oil, or one or more liquid or solid mosquito larvicides, ovicides, pupicides, insecticides, pesticides, biological control agents, microbial control agents, pathogens, parasites, conventional toxicants, and insect growth regulators, by high-speed or high-shear agitation, or salt/electrolyte conditioning procedures with mild agitation, to produce flowable, homogeneous and stable, single-, joint- or multiple-action, variable-viscosity aqueous- or oil-base formulations for single- and multi-stage mosquito control in the aquatic environment. Flowable formulations produced in this manner with one or more superabsorbent polymers can be premixed and stored for prolonged periods and will not require constant vigorous spray system agitation for effective field application of the aqueous- or oil-base suspensions/ high-shear compositions.

Surprisingly, the data indicates that aqueous formulations of Super Sorb and Arosurf® MSF generally produced faster control of larvae of Aedes taeniorhynchus than Arosurf® MSF alone. The data suggests that the flowable aqueous superabsorbent polymer formulation remained homogeneous and stable after initial mixing and may produce an activation or larvicidal enhancement mechanism for Arosurf® MSF against this mosquito species in the water qualities tested. It should be noted that the superabsorbent polymer alone showed no significant larvicidal activity. In general, some larvicidal enhancement was observed in tests against Culex quinguefasciatus with aqueous formulations of Super Sorb and Arosurf® MSF. Tests against this species in fresh water showed initial larvicidal enhancement or comparable larvicidal efficacy over the test period when the superabsorbent polymer/Arosurf® MSF formulations were evaluated against Arosurf® MSF alone (i.e., without polymer). It should be noted that larvae of the Ae. taeniorhynchus are significantly more sensitive to Arosurf® MSF than Cx. quinguefasciatus. However, it should be noted that the salt marsh mosquito Ae. taeniorhynchus is the main pest mosquito in Lee County as well as in other coastal counties of Florida and other parts of the U.S.A.

EXAMPLE I

A flowable formulation was prepared in this example. Water, Arosurf® MSF, and Super Sorb were mixed together in a glass beaker with a laboratory blender containing a shearing blade to produce an aqueous formulation that could be used to control mosquito larvae and pupae at application rates recommended for the control of immature mosquitoes. For example, 0.4 g of Super Sorb were added to 94.4 g of water purified by reverse osmosis filtration (RO) while mixing at 1800 rpm for 30 sec. Mixing speed was increased to 2400 rpm while adding 5.2g of Arosurf® MSF. Mixing was continued for 10 min. Observations indicated that the Arosurf® MSF was homogeneously suspended in the water with the addition of 0.4% Super Sorb superabsorbent polymer to form a milky semi-viscous flowable formulation. This formulation was easily sprayable from a plastic hand-pump sprayer. No visible stratification or separation of the formulation components was observed one hour after preparation. However, aqueous Arosurf® MSF formulations containing no Super Sorb and mixed in a similar manner began to separate into an Arosurf® MSF and a water phase within several minutes after blending. The non-superabsorbent polymer formulation had separated into 2 distinct phases 1 hour after mixing, and required reagitation/remixing to effectively resuspend the 2 components into a uniform mixture. The Super Sorb-base milky formulation appeared stable, i.e., the Arosurf® MSF and water did not appear to have separated, when observed at one, two, three and four week post-mixing intervals. Distinct separation of the Arosurf® MSF and water in the non-Super Sorb formulation was observed at each of these intervals, even though this formulation was resuspended (remixed) after each weekly observation.

EXAMPLE II Flowable formulations composed of 0.5-0.8% Super Sorb (0.5-0.8%) and Arosurf® MSF, B.t.i. (Bactimos® Primary Powder, Vectobac®-AS, or Teknar®) and reverse osmosis (RO) water or well water, as well as Super Sorb (0.5-0.8%), Arosurf® MSF, B. sphaericus (BSP-1), and RO or well water were prepared for application of active ingredients at rates recommended on the labels for control of larvae or pupae by blending techniques similar to those described in Example 1. The order of addition of the components, mixing speed (1200 -4200 rpm), mixing intervals (start/stop), and mixing duration (15 sec - 30 min) were dependent on the concentration of Super Sorb, concentration of Arosurf® MSF, water quality, and on the type, concentration and/or formulation of bacillus used in the aqueous composition. Results were similar to Example I, that is, observations indicated that homogeneous and persistent (non-separating) suspensions of the B.t.i. or B. sphaericus and Arosurf® and water resulted at one, two, three, and four week post-mixing observation periods while non-superabsorbent polymer formulations of B.t.i. or B. sphaericus mixed with Arosurf® MSF and water separated into two or three distinct layers within 1 hr post-mixing. In fact, component partitioning began almost immediately after mixing. The duration and speed of mixing did not improve the compatibility or suspendability of one or more active ingredients in the non-superabsorbent polymer formulations.

EXAMPLE III For an illustration of a flowable oil-base formulation of the present invention, 310g of Arosurf® MSF nonpetroleum oil, 310 g of Aquastore® F polymer, and 10g of B.t.i. (Vectobac® Technical Powder) were mixed in a beaker with a small electrically-powered mixer for ca. 10 min. When a drop of this semi-viscous non-aqueous (i.e., oil base) flowable formulation was added to water with an eye dropper, a bead of gel formulation (specific gravity > 1) instantly formed upon contact with the water and slowly expanded as the polymer absorbed water, thereby releasing both active agents (i.e., B.t.i. and Arosurf® MSF).

EXAMPLE IV

The comparative mosquito-controlling efficacy of the flowable, high-shear, aqueous formulation of Arosurf® MSF and Super Sorb superabsorbent polymer was determined in a series of bioassays against larvae and pupae of Ae. taeniorhynchus and Cx. quinquefasciatus in a variety of -water qualities. Aqueous formulations were prepared in a manner similar to that described in Example I.

Bioassays were conducted in 400 ml glass beakers containing 250 ml of test water and 2nd to 4th instar larvae, or combinations, of 5 larvae and 5 pupae (3 replications/ formulation). Aqueous formulations containing Super Sorb were allowed to sit unmixed for one hour post-blending and were remixed while aqueous formulations containing no Super Sorb were vigorously hand shaken for 1 minute prior to application. Flowable formulations were applied to the water surface with a glass pipette or microsyringe at application rates recommended for the control of mosquito larvae and pupae. Bioassays were conducted in a room maintained at 80° F (ambient) and 80% Rh.

Results of bioassays against larvae and pupae of Ae. taeniorhynchus and Cx. quinquefasciatus are presented in Table 1. In general, the data indicated that che Arosurf® MSF aqueous formulations, containing varying amounts of Super Sorb killed 2nd-4th instar larvae of Ae. taeniorhynchus as quick or faster than technical Arosurf® MSF and/or aqueous Arosurf® MSF containing no Super Sorb. Similar findings were recorded in bioassays against 2nd-4th instar larvae of Cx. quinquefasciatus; however, these were not as dramatic as the results obtained with larvae of Ae. taeniorhynchus. Water quality of the formulation diluent and/or mosquito habitat, superabsorbent polymer concentration, and larval instar were shown to affect the rate of larvicidal action. Also, preliminary high-shear mixing results with Super Sorb, Aridall® 1092, Water Lock® G-100, or Aqua Keep® J-500 superabsorbent polymers and Arosurf® MSF, bacilli and water indicated that the type of polymer (i.e., the water absorbing characteristics) will affect the optimum percent concentration of superabsorbent polymer required for effective aqueous suspension of the formulation ingredients.

EXAMPLE V As an alternative, or an addition to, vigorous or high-spead/high-shear mixing, to reduce viscosity and enhance the suεpendability and/or mixing compatibility of one or more insecticidal or non-insecticidal components in an aqueous superabsorbent polymer-base formulation, additional viscosity/suspendability modification tests were conducted in 100 ml glass medicine bottles to determine if electrolytes/salts (e.g. 0.1 - 0.5%) such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride or sodium sulf ite could be used in combination with mild agitation (i.e., not high-shear) to decrease the viscosity (i.e., increase the flowability or fluidity) of variable-viscosity formulations (100 g total prepared) composed of reverse osmosis water, 5% Arosurf® MSF, and 0.5% of a superabsorbent polymer such as Aqua Keep® J-500, Super Sorb, or Aridall® 1092, with or without B.t.i. (Vectobac® -AS) or 5% B. sphaericus (BSP-1), without adversely affecting the suspendability or mixing compatibility of the formulation components. Insecticidal ingredients were formulated for aqueous application to the water surface at 5.0 gal/acre at rates that were recommended on the labels for the control of mosquito larvae and pupae.

Results indicated that the salt/electrolyte concentration and type used in the aqueous formulation was dependent on the type (and concentration) of superabsorbent polymer and the type and concentration of insecticidal ingredients in the formulation. Also, the tests indicated that the order of adding the formulation components in water, as well as the type of salt/ electrolyte used, could affect the ease of mixing, suspendability, or stability of the ingredients. In general, results suggested that stable, homogeneous formulations of water, Arosurf® MSF, a superabosrbent polymer, with or without a larvicidal bacillus, and an electrolyte/salt could be formed with mild agitation (i.e., hand-shaking). It should be noted that no separation, partitioning, or clumping of the components was observed at 24 hr post-mixing.

Compartive bioassays to determine the mosquito-controlling efficacy of hand-shaken (30 sec) aqueous formulations composed of 5.0% Vectobac® -AS or BSP-1 and 5.0% Arosurf® MSF and 0.5% Super Sorb or Aqua Keep® J-500 with 0.1% sodium chloride or sodium sulfite against 3rd-4th instar larvae and pupae of Cx. quinquefasciatus resulted in 100% mqrtality within 24-48 hr post-treatment. One hundred percent control of mixed larvae (3rd-4th instar) and pupae of Ae. taeniornychus was also observed in similar tests with the B.t.i. Vectobac® -AS) formulation within 24 hr post-treatment. The same results were also recorded with the above compositions that were formulated with high shear mixing but without a salt/electrolyte.

EXAMPLE VI Additional mixing compatibility tests were conducted in 100 ml glass medicine bottles with compositions of 0.5 g Aqua Keep® J-500, Water Lock® A-100, or Aquastore®F, and 5 g Arosurf® MSF, 9.5 g 2,4-D, and 85 g R.O. water indicated that flowable variable-viscosity superabsorbent polymer formulations composed of a mosquito larvicide/pupicide and a herbicide could be made with mild agitation (i.e., vigorous hand-shaking for 30 sec). No separate salts/electrolytes were added to the flowable formulation since the active ingredient in the E.P.A. registered herbicide formulation is 65.6% dimethylamine salt of 2,4-Dichlorophenoxyacetic acid. Flowable formulations were prepared for application of the active ingredients at label recommended rates, i.e., ca. 0.25 gal/acre Arosurf® MSF and 0.5 gal/acre 2,4-D, at 5.0 gal/acre total formulation. No clumping, stratification, or separation of the components in the flowable superabsorbent polymer formulations were noted at 24 hr post-mixing, even though vigorous or high-shear agitation was not employed. Surface spreading activity of Arosurf® MSF was verified by the use of talc (see Example VII). Formulation viscosity varied with the type of superabsorbent polymer; however, all formulations were very flowable.

EXAMPLE VII The slow release potential of an insecticidal ingredient from formulation of variable viscosity superabsorbent polymer was determined by laboratory spreading rate evaluations according to procedures established by Levy et al. 1984, Mosquito News 44:419-422. Super Sqrb (2 g) and an R.O. water-10% Arosurf® MSF mixture (10 g) were blended with a high-shear dyna mixer. This aqueous formulation was applied to the water surface at the one end of a stainless steel pan containing 7,570 ml of R.O. well water that had been evenly dusted with 0.15 g baby powder-type talc at a formulation rate of ca. 0.53 g/pan or ca. 026 gal/acre Arosurf® MSF (3 replications). The spreading rates of Arosurf® MSF from the aqueous superabsorbent polymer formulation were compared to the spreading rates for technical Arosurf® MSF applied at 0.26 gal/acre. The comparative slow release potential of the formulation was determined by the average time in seconds needed for the formulation to move or translocate the powder to the opposite perimeter of the test pan. Results indicated that the floating aqueous Super Sorb/Arosurf® MSF formulation translocated the powder to the perimeter of the pan in an average of 33.3 sec, while technical Arosurf¶ MSF translocated the powder in 5.3 sec; thereby indicating the slow release of potential Arosurf® from an aqueous superabsorbent polymer formulation. The principles, preferred embodiments and modes of operation of the present invention have been described in the foregoing specification. The invention which is intended to be protected herein, however, is not to be construed as limited to the particular forms disclosed, since these are to be regarded as illustrative rather than restrictive. Variations and changes may be made by those skilled in the art without departing from che spirit of the invention.

Claims

WHAT IS CLAIMED IS

1. A variable viscosity flowable insecticidal delivery composition for controlling a population of aquatic environment insects in preflood or flood conditions comprising:

(a) at least one superabsorbent solid organic polymer comprising hydrophilic acrylamide or acrylate polymers (co-polymers or ter-polymers) which absorb over 100 times their weight in water,

(b) at least one different insecticidal agent, and

(c) water or oil, said polymer, agent and water or oil being present as a flowable formulation wherein the agent is present in a total amount effective to control the population of aquatic environment insects.

2. The composition of claim 1, wherein the valuable-viscosity flowable formulation is formed by vigorous or high-shear mixing, and the superabsorbent polymer is substantially water-insoluble.

3. The composition of claim 2, wherein said superabsorbent polymer comprises a starch graft polymer, copolymer or ter-polymer.

4. The composition of claim 2, wherein said superabsorbent polymer is selected from the group consisting of: an acrylamide sodium acrylate copolymer; a hydrolyzed starch-polypolyacrylonitrile; 2-propenenitrile, homo-polymer, hydrolyzed, sodium salt; poly (acrylamide-co-sodium acrylate); poly (2-propenamide-co-2-propanoic acid, sodium salt); starch--g-poly (acrylonitrile); starch-g-poly (acrylamide-co-sodium acrylate); a starch, acrylonitrile copolymer; poly-2-propanoic acid, sodium salt, potassium salt or mixed sodium/aluminum salt; poly(2-propenamide-co-2- propanoic acid), sodium salt; starcα-g-poly(2-propenamide-co- 2-propanoic acid), potassium salt; starch-g-poly(2- propenamide-co-2-propanoic acid); starch-g-poly(2-propenamide-co-2propenoic acid), sodium salt; crosslinked modified polyacrylamide; or crosslinked acrylics; and mixtures thereof.

5. The composition of claim 1, wherein the variable-viscosity flowable formulation is formed by an additive amount of an electrolyte/salt, in the absence of virorous or high-shear mixing.

6. The composition of claim 1, comprising at least one compound selected from the group consisting of: ovicides; larvicides; pupicides; insecticides; pesticides; toxicants; biological control agents; microbial control agents; pathogens, parasites; chemosterilants and insect growth regulators with or without active or inert additives or diluents such as herbicides, attractants, repellants, pheromones, alcohols, solvents, surfactants, etc.

7. The composition of claim 1, wherein the ratio of superabsorbent polymer to water is from about 0.001:100 to 1:1.

8. A variable-viscosity flowable mosquitocidal delivery composition for controlling a population of aquatic environment mosquitoes comprising: at least one superabsorbent solid organic polymer selected from the group consisting of hydrophilic acrylamide and acrylate polymers which absorb over 100 times their weight in water, at least one different insecticidal agent comprising a film-forming agent, and at least one additional compound selected from the group consisting of ovicides; larvicides; pupicides; insecticides; pesticides; toxicants; chermosterilants; biological control agents; microbial control agents; pathogens; additives such as herbicides, attractants, repellents, pheromones, alcohols, solvents, etc., said composition being in the form of a flowable aqueous- or oil-base formulation wherein said polymer, agent and additional compound being present in a cotal amount effective to control the population of aquatic environment mosquitoes.

9. The composition of claim 8, wherein the ratio of superabsorbent polymer to water is about 0.01:100 to about 0.5:1.

10. The composition of claim 9, wherein said superabsorbent polymer is selected from the group consisting αf: an acrylamide sodium acrylate co-polymer; a hydrolyzed starch-polyacrylonitrile; 2-propenenitrile, homo-polymer, hydrolyzed, sodium salt or poly(acrylamide-co-sodium acrylate) or poly(2-propenamide-co-2-propanoic acid, sodium salt); starch-g-poly(acrylonitrite) or starch-g-poly(acrylamide-co-sodium acrylate; a starch, acrylonitrite copolymer poly-2-propanoic acid, sodium salt; poly (2-propenamide-co-2-propanoic acid), sodium salt; starch-g-- poly (2 propenamide-co-2-propanoic acid), potassium salt; starch-g-poly(2-propenamide-co-2--propanoic acid); starch-gpoly(2-propenamide-co-2-propanoic acid), sodium salt or sodium/aluminum mixed salt; crosslinked modified polyacrylamide; or crosslinked acrylics; and mixtures thereof.